The federal government faces 35 compensation claims from families affected by groundwater contamination by firefighting foam from air force bases.
Thirty-three cases are being negotiated out of court while two are lawsuits, a Senate estimates hearing was told on Wednesday.
A Defence Department official said there was no class action under way.
The government allocated $55 million in this year's budget to a drinking water program for property owners surrounding defence bases at Oakey in Queensland, Williamtown in NSW, Tindal in the Northern Territory and Pearce in Western Australia.
The hearing was told the money was yet to be carved up among the locations.
It will cover the installation of water tanks, connections to town water supplies and water use fees for several years.
About 50 water tanks had been installed at properties near Katherine in the NT, with 20 more to go.
The government's independent expert health panel has concluded there is limited or no evidence exposure to Per-and poly-fluoroalkyl substances (PFAS) contaminations causes disease or increases cancer risks.
The department is investigating other foam alternatives to PFAS chemicals.
Meanwhile, a new parliamentary inquiry has been set up to investigate the federal government's response to the contaminations.
Public submissions close on July 6.